12-Foot LST Test Log

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Complete log book #1 and log book #2.


[top] Model #1: North American B T-9A

The North American B T-9A and its Navy counterpart, the NJ-1, are basic training airplanes of the low-wing type with a fixed, semi-faired landing gear and split flaps.

The lack of lateral stability and the peculiar stalling characteristics of the airplane contributed to a number of fatal accidents. The NACA made some preliminary observations on the lateral behavior of a airplane. During these a sharp dropping of the right wing was noticed at low speeds.

Commander Diehl, Bureau of Aeronautics, Navy Depart­ment, recommended that a model of the airplane be tested in the NACA 5-foot free- tunnel to determine the effect of dihedral on the stall and wing dropping ten­dencies.

Test Log Entry

[top] Model #2: Brewster XF2A-1

The Brewster XF2A-1 airplane was a midwing type navy shipboard fighter airplane with a very deep, stubby fuselage. The landing flaps were narrow-chord split flaps covering about 48 percent of the wing span and the ailerons were hence small­ span (33 percent) wide-chord surfaces. The tail surfaces of the airplane employed an unusually large moveable portion.

Tests of a model of the XF2A-l in the NACA 5-foot free-flight tunnel to determine the effects of varying the dihedral angle and the vertical tail area were requested by Commander Diehl of the Bureau of Aeronautics, Navy Department.

Test Log Entry

[top] Model #4: Vought-Sikorsky Zimmerman No. V-173 (The Flying Pancake)

The V-173 is a flying-wing type airplane of extremely low aspect ratio and almost circular plan form with two large propellers located near the wing tips.

While Charles H. Zimmerman was at NACA he made some tests on wings of very low aspect ratio. Those tests inspired the design of the V-173. The plan form of the airplane was developed from a circle by straightening out the 25 percent chord line. A pilot's enclosure in the center, two propeller-shaft housings near the tips, and twin vertical tails at the trailing edge of the wing were added. The two large propellers near the wing tips turning up in the center to oppose the tip vortices pro­duced only a slight improvement in the efficiency of the wing.

Control was obtained on the original model by means of two hinged trailing edge sections of the wing which could be operated together as elevators or oppositely as ailerons, and directional control was provided by the twin rudders.

The V-173 was also tested in the Full Scale Tunnel. For more on the V-173, see Wikipedia the Wikipedia article.

Test Log Entry

V-173 in Full Scale TunnelV-173.jpg19022.jpg19325.jpg20611.jpg20613.jpg

[top] Model #6: Curtiss P-36A

The Curtiss P-36 Hawk, also known as the Curtiss Hawk Model 75, was an American-designed and built fighter aircraft of the 1930s and 40s. A contemporary of both the Hawker Hurricane and Messerschmitt Bf 109, it was one of the first of a new generation of combat aircraft—a sleek monoplane design making extensive use of metal in its construction and powered by a powerful radial engine. Obsolescent at the onset of World War II and best known as the predecessor of the Curtiss P-40 Warhawk, the P-36 saw only limited combat with the United States Army Air Forces, but it was used more extensively by the French Air Force, both during the Battle of France and by the Vichy French, and also by the British Commonwealth (where it was known as the Mohawk), and Chinese air units. Several dozen also fought in the Finnish Air Force against the Soviet Air Forces. With around 1,000 aircraft built, the P-36 was a major commercial success for Curtiss.

YouTube Video

Test Log Entry

[top] Model #7: SBN-1

The SBN-1 is a conventional midwing cantilever monoplane with an air-cooled radial engine, retractable landing, gear and split diving flaps.

Tests of a model of the SBN-1 in the free- tunnel were requested by Comm. Diehl, Bureau of Aeronautics, U.S. Navy, to determine the usefulness of the free- tunnel in the development of navy airplanes.

Models of the SBN-l had previously been tested in the laboratories of the Washington Navy Yard.

Test Log Entry

[top] Model #8: Vought-Sikorsky XF4U-1

The XF4U-l is a single place navy fighter airplane of the low-wing monoplane type employing an inverted-gull wing.

The XF4U-1 was originally designed as a high-performance ship-board fighter of 41 foot span, 8598 pounds gross weight and employing a Pratt and Whitney R-2800-2 engine rated at 1800 take-off horsepower and 1500 continuous horsepower. The production model of the airplane weighed approximately 11,000 pounds and employed an engine rated at 2000 take-off horsepower and 1800 continuous horsepower. The aileron span was increased 20 inches in accordance with the recommendations of the free- tunnel and research maneuvers.

Test Log Entry

[top] Model #11: Seversky P-41

The Seversky XP-41 was a fighter aircraft built in the United States in 1939. A single prototype was modified from the last production Seversky P-35 by adding a new streamlined canopy, a Wright R-1830-19 engine with a two-speed supercharger, and revised landing gear. XP-41 first flew in March 1939. The aircraft was developed in parallel with the P-43 Lancer, and work was stopped when the USAAC showed a preference for the latter.

Test Entry Log

[top] Model #13: Laminar Flow Airplane

The NACA laminar-flow airplane was a high-wing, pusher monoplane with exceptionally small tail surfaces. The airplane was designed to test the newly developed. NACA low-drag airfoil, because neither the army or navy showed sufficient interest to test the airfoil.

The whole airplane was designed to prove the low-drag airfoil, hence pusher propellers were used to eliminate the undesirable effects of the slipstream on the flow over the wing. The horizontal and vertical tail surfaces (each 5 percent of the wing area) were designed to give low static stability on the premise that a smoother riding airplane could be achieved inasmuch as gusts would produce straight, sideways, or vertical displacements rather than yawing or pitching motions.

Test Entry Log

[top] Model #14: Northrop N-1-M

The Northrop N-1-M, also known by the nickname "Jeep," was an all-wing-airplane with a very thick highly tapered wing with turned down tips and two pusher propellers driven by internal engines. It was a small-scale flying mock-up of a proposed bomber design.

Directional stability was provided by means of the extreme negative dihedral of the wing tips and directional control was provided by rudders on these turned down tips. Conventional ailerons were used for lateral control and were deflected together as elevators to provide longitudinal control. These combined elevator and aileron surfaces are called "elevons."

In 1942 the N-1-M was the latest of a series of tailless airplanes developed by Northrop from 1928 and represented the ultimate in tailless airplanes since all parts of the airplane were enclosed in the wing. Except for cooling ducts, shift housings, etc. all parts of the airplane contributed to its lift. The N-1-M was an experimental aircraft used in the development of the flying wing concept.

YouTube Video

Test Log Entry

[top] Model #15: Materiel Center Tailless Glider

The Materiel Center tailless glider No. 364, in its original configuration, was a flying-wing-type airplane with a swept-back tapered wing and fins on the upper surface near the tips.

The No. 364 was a model of a proposed tailless bomber. The model, however, was built without motor nacelles or movable controls, and was tested in gliding at Wright Field. The model was then sent to the free-flight tunnel to determine to what degree the condition in the free-flight tunnel represented actual gliding flight in free air. Later the free-flight tunnel investigation was extended to include a study of means of improving the stability of the model in controlled flight.

The stability of the model was determined to be satisfactory for gliding flight. For controlled flight, however, the longitudinal stability was too low, the lateral stability was unsatisfactory and the directional stability was inadequate.

Test Log Entry

Free-Flight Tunnel Tests of the Materiel Center Tailless Glider Model No. 364. John P. Campbell and Thomas A. Hollingworth. 1942.

[top] Model #17: Northrop XP-56

The Northrop XP-56 is a tailless-type airplane with the midwing attached to a short fuselage and with small low-aspect-ratio fins and dual-rotation pusher propellers. It has many of the features originally incorporated in the Northrop N-1-M including turned-down wing tips for increased directional stability, wing-tip rudders for directional control, and combined aileron and elevator control surfaces called elevons. The wing-tip rudders were of the split type. The original design of the XP-56 was guided by tests of various wing and wing-fuselage combinations for tailless airplanes in the GALCIT wind tunnel.

The free- tunnel recommended a redistribution of elevon area to improve lateral control, higher aspect ratio fins for greater directional stability and a combination of slots and flaps to increase the maximum lift coefficient. A film record of the free- tunnel tests was sent to Northrop as had been done on the N-1-M. Northrop appeared highly pleased with the results. Obviously they considered the free- tunnel pessimistic stance the N-1-M had better behavior in full-scale tests than in the free- tunnel. Consequently no changes were made in the airplane since it had performed better in the free-flight tunnel than the N-1-M and they were satisfied with the N-1-M.

Test Log Entry

[top] Model #20: North American XB-28

The direction of rotation of the propellers on multi engine airplanes is becoming of greater importance because of the increase in engine nower and the accompanying effects on airplane stability. Recent tests (reference 1) have shown that, although the direction of propeller rotation has a pronounced effect on both static longitudinal and lateral stability, no single mode of rotation was found to give the best results for all conditions. In order to provide more data on the actual behavior of a twin-engine airplane for various modes of propeller rotatiton the free- tunnel Project No. 20 was inaugurated as an NACA research project. The effects of flap deflection, various amounts of power and various amounts of vertical tail area were also studied.

Test Log Entry

[top] Model #20-5

[top] Model #21: Curtiss-Wright 24-B

The Curtiss-Wright 24-B is a full-scale flying mock up of the Curtiss-Wright XP-55 airplane with reduced weight and power. It retains, with several minor modifications, the original design of the XP-55 which is a "tailless" pusher airplane with a free-floating nose elevator, cowl fins and rudders to provide directional stability and control located about 1/4-span outboard of the fuselage at the trailing edge of the wing.

Wind-tunnel tests of models of the XP-55 were conducted at the Massachusetts Institute of Technology, and later in the NACA 19-foot pressure tunnel. tests of the 24-B were conducted at Muroc Lake.

The XP-55 was designed with the idea of eliminating all possible effects of the propeller slipstream on the flow over the wing of the airplane in order to increase the efficiency of its laminar flow airfoil. The tests, which indicated that the 24-B was flyable, also indicated the advantages and disadvantages of the airplane. The primary advantage seemed to be the ability to turn the nose of the airplane inside a tight turn, and also the differential action of the rudders created somewhat of a "flat spot" on the control near neutral position. Both of these features will be an asset to gunnery. The principle disadvantage was encountered with the control stick fixed to the free-floating elevator. With this direct elevator control the stick moved back and forth as the elevator trimmed with gusts. Other difficulties encountered with the 24-B were low directional stability, too little lateral control, and excessive dihedral.

Test Log Entry

[top] Model #22: Northrop Project 6

The Northrop project 6 design was a midwing monoplane with a submerged engine driving a propeller which was located behind the conventional tail surfaces. The design originated at the NACA inspired by two principle ideas:

1. To design an airplane incorporating a submerged engine installation for increased efficiency of cooling.

2. To eliminate the undesirable effects of the propeller slipstream on stability and control.

The increased efficiency in cooling the submerged engine was gained by taking in sufficient cooling air through a small opening in the nose of the airplane and expanding it slowly to the engine.

The original design of the airplane incorporated a wing with an aspect ratio of twelve, for high efficiency, and an NACA low-drag aileron. The pusher design afforded the optimum operating conditions for the low-drag airfoil, as there was no slipstream to destroy the laminar flow over the wing.

Test Log Entry

[top] Model #24: Controlled Glide Bomb

The National Bureau of Standards' controlled glide­ bomb was similar in design to a conventional airplane. The bomb is totally enclosed within the fuselage to which was attached a high mid-wing and a horizontal tail with end plates to provide directional stability. Since low speed is not required, the wing loading is high. A single set of control surfaces, called "elevons", provide both lateral and longitudinal control.

Test Log Entry

[top] Model #25 & 26: Wing-Loading Investigation

This investigation was to study the effects of wing-loading on lateral stability and control. John P. Cambell supervised the design of the model and Charles Seacord calculated the stability boundaries. It was found that the only stability factor affected was the relative density factor.

Test Log Entry

A test video of a XF4F-3 is also available.

[top] Model #27: Towed Glider Stability

Towed gliders may have many military and commercial applications such as carrying additional cargo, personnel, bombs, or extra fuel which would increase the load-carrying capacity or range of existing airplanes. A severe limitation to the use of the towed glider, however, is the problem of obtaining satisfactory stability of the towed aircraft. This lack of stability has made it necessary, in most cases that each glider have its own pilot to make the necessary corrections to hold the glider on its course. In blindtowing, either at night or in bad weather, the glider pilot loses orientation with the towing airplane and thus has difficulty in avoidijng accidents. On long trips the pilot fatigue is objectionable. It appeared desirable, therefore, to attain an inherently stable towed glider. Some success has been attained with a single towline, but the problems have been considerable.

In an effort to obtain an inherently stable towed glider a system of twin parallel towlines was devised with the towlines attached near the wing tips of the glider and on its Y-axis. This system provides restraint in yawing and provides added lateral stability through the action of the towlines.

Test Log Entry

[top] Model #28: Bell XP-63 V-Tail Model

The Bell XP-63 V-Tail model was a low-wing, single-seater fighter, with engine amidship, driving a tractor propeller by a long extension shaft. A 37mm cannon was arranged to fire through the propeller hub. The XP-63 V-Tail Model evolved from the P-39 series airplanes, and is essentially a slightly heavier P-39. It has a low-drag airfoil section and was designed as a long-range fighter or interceptor pursuit. The external geometry of the airplane was more or less repre­sentative of current practice for the time at which it was designed.

The Bell P-63 Kingcobra (Model 24) was a United States fighter aircraft developed in World War II from the P-39 Airacobra in an attempt to correct that aircraft's deficiencies. Although the aircraft was not accepted for combat use by the United States Army Air Forces, it was successfully adopted by the Soviet Air Force.

Test Log Entry

[top] Model #29: Fairchild XR2K-1

The Fairchild XR2K-1 was a high-wing transport airplane built for the U.S. Navy and Marines. The airplane was tested in the Full Scale Tunnel as well. See Test 58, Test 60, Test 63, Test 71 Test 122.

Additional information on the Fairchild XR2 models, see Early Flight Research XR2K-1.

For additional information, see these reports.

1943 NACA Wartime Report: Flight Tests of an All-Movable Vertical Tail on the Fairchild XXR2K-1 Airplane

1944 NACA Wartime Report: A Flight Investigation of Short-Period Longitudinal Oscillations of an Airplane with Free Elevator

[top] Model #30: Effects Of Mass Distribution On Lateral Stability

The effects of mass distribution on lateral stability and control characteristics of an airplane were determined to verify past theoretical investigations and to determine the effects of the stability changes on general behavior. Theoretical investigations had been made to determine the effects of large increases in momentents of inertia on lateral stability. These increases in yawing and rolling moments of inertia, caused by a redistribution of weight along the wing, had been brought about because of the changes in design from single to multi-engine airplanes and an increased use of wing guns and fuel tanks.

Test Log Entry

[top] Model #31: XP-59

The Bell XP-59 was an unusual United States fighter aircraft design by the Bell Aircraft Corporation. It was submitted as part of a United States Army Air Corps competition held in the winter of 1939.

The fuselage was round and barrel-shaped, with the pilot in the nose and the piston engine behind him, driving a pair of contra-rotating propellers at the rear of the fuselage in a pusher configuration. The wings were mid-fuselage and swept back at an angle of 20 degrees, and the horizontal stabilizer was connected at each end to booms from the wings, similar to the P-38 Lightning's layout.

[top] Model #32

[top] Model #33

[top] Model #34: Flaps For Tailless Airplanes

One of the principle arguments advanced against tailless airplanes, is that their maximum lift coefficient attainable in trimmed is low. This is believed to be true because they either have no flaps or lose much of the added increment of lift resulting from flaps in trimming out the diving moment caused by the flaps. Hence, an analytical investigation was made in the free- tunnel to determine the relative merits of various wing plan forms and methods of trimming out the flap diving moment.

Test Log Entry

[top] Model #35

Tailless Bomber #35

[top] Model #36

Kaiser Tailless Model

[top] Model #37

[top] Model #38: CLMax Investigation

It had been proposed that members of the free­--tunnel staff conduct a performance comparison between tailless and conventional airplanes. In order to compare the maximum lift coefficients of these airplanes equally, it was believed that the tail surfaces, perhaps, should be added to the wing area. This was done to approximate values of CLMax relative to the CLMax/CDMin ratio. After the data were obtained, it was decided that it might be use­ful to designers and a separate bulletin was published.

Test Log Entry

[top] Model #39

[top] Model #40 Consolidated Tailess Bomber

Investigation of Stability and Control Characteristics of Models of the Consolidated Vultee Tailless Airplanes in the Langley Free-Flight Tunnel-I. Bernard Maggin. 1945. MR L5B03.

Investigation of Stability and Control Characteristics of Models of the Consolidated Vultee Tailless Airplanes in the Langley Free-Flight Tunnel-II. John W. Paulson and Bernard Maggin. 1945. MR L5E07a.

Investigation of Stability and Control Characteristics of Models of the Consolidated Vultee Tailless Airplanes in the Langley Free-Flight Tunnel-III. Hubert Drake. 1945. MR L5F13a.

[top] Model #40-3 Consolidated Tailess Bomber

[top] Model #40-A-2

[top] Model #41: GB-5 Controllable Glide Bomb

At the request of the Army Air Forces, Materiel Command, the NACA undertook the job of assisting in the development of a type GB-5 controllable glide bomb equipped with a "target-seeking" device. At the time that the NACA undertook the project, the Army Air Forces had made several drops of full-scale type GB-5 glide bombs guided by a target seeker. The behavior of these bombs had been unsatisfactory primarily due to sideslip­ping oscillations of large amplitude which would mean missing the target by a considerable distance.

The first phase of the NACA investigation to be undertaken was a theoretical analysis by the stability analysis section of the stability and control characteristics of the bombs under automatic control by the "target seeker". A control combination which would give satisfactory behavior of the bomb controlled by the "target seeker" was determined by the theoretical analysis. This configuration when applied to a bomb by the Army Air Forces did give satisfactory behavior.

In connection with the theoretical analysis, it was found desirable to know the, effects of certain modifi­cations to the static stability characteristics of the bomb. Hence a 1/5-scale, solid-mahogany, model of the bomb was sent to the free- tunnel by the Materiel Command, Army Air Forces, for wind­ tunnel tests on the six-component free--tunnel balance.

All changes made to the model were so planned as to obtain stability changes with simple structural modifications in order to permit full use to be made of full­ scale bomb units already manufactured.

Test Log Entry

[top] Model #42: Aermca GB-5 Glide Bomb

A glide bomb is an aerial bomb modified with aerodynamic surfaces to modify its flight path from a purely ballistic one to a flatter, gliding, one. This extends the range between the launch aircraft and the target. Glide bombs are often fitted with control systems, allowing the controlling aircraft to direct the bomb to a pinpoint target.

[top] Model #43

[top] Model #44: GB-7B Controllable Glide Bomb

At the request of the Army Air Forces, Material Command, force tests were made in the NACA free- tunnel on a 1/5-scale model of a type GB-7B controllable glide bomb. This glide bomb is a modified version of the type GB-5 controllable glide bomb previously tested in the NACA free- tunnel and reported on in reference 1. The GB-7B glide bomb represents a GB-5 bomb unit to which a fuselage nose extension has been added and on which fuselage fairings have been placed extend­ing from the wing to the horizontal tail surfaces between the twin tail booms. The purpose of the tests was to determine the effects of the fairing modifications on the static longitudinal and directional stability characteristics of the glide bomb. Results of the tests were compared with GB-5 test results of reference l.

Test Log Entry

[top] Model #45

[top] Model #46

[top] Model #48

[top] Model #50 A

[top] Model #50 B

[top] Model #53

[top] Model #54

[top] Model #54A

Model #54A Glider

[top] Model #56

[top] Model #57

[top] Model #57A

[top] Model #57-AN

[top] Model #57-A and #60

[top] Model #58

[top] Model #60-A

[top] Model #61

[top] Model #62

[top] Model #63

[top] Model #64

[top] Model #65

[top] Model #66-9

[top] Model #67

[top] Model #68 A

[top] Model #69: XF-85

The McDonnell XF-85 Goblin was a prototype fighter aircraft, conceived during World War II by McDonnell Aircraft. It was intended to be carried in the bomb bay of the giant Convair B-36 "Peacemaker" bomber as a defensive "parasite fighter". During World War II, Luftwaffe fighters provided stiff opposition for Allied bombers. The XF-85 was a response to a United States Army Air Forces (USAAF) requirement for a parasite fighter capable of being carried within the Northrop XB-35 and B-36 then underdevelopment. Two prototypes were built, which underwent testing and evaluation during 1948, three years after the war. Flight tests showed promise in the design, although the aircraft's inherent design flaws associated with parasite fighters were never resolved. It was swiftly canceled due to a number of factors, and are now museum exhibits.
YouTube Video

[top] Model #71

[top] Model #73: XF74-1

[top] Model #74: Convair XA-44

This aircraft was redesignated the XB-53 in 1949.

[top] Model #75: P-92 Model

[top] Model #77

[top] Model #78

[top] Model #79

[top] Model #82

[top] Model #83-B

[top] Model #86

[top] Model #87

[top] Model #88

[top] Model #89

[top] Model #93

[top] Model #94

[top] Model #95

[top] Model #98 McDonnell F3H

[top] Model #99

[top] Model #101

[top] Model #102

[top] Model #103 Douglas F4D Skyray

Appears to be test on leading-edge slats

[top] Model #104 B-36/F-84 'Tom-Tom'

[top] Model #108 Convair XFY-1 Pogo

Various test designs and the final configuration

[top] Model #110

[top] Model #112

[top] Model #119

[top] Model #119A - F102A

[top] Model #121: 110-T-Model

This model was tested in the 12-Foot Low Speed Tunnel as well as the Full Scale Tunnel during 1954.

[top] Model #122

This model was tested in the 12-Foot Low Speed Tunnel as well as the Full Scale Tunnel during 1954.

[top] Model #124

[top] Model #128

[top] Model #135

[top] Model #138

[top] Model #139

[top] Model #141

[top] Model #143

[top] Model #144: R7D/RVD Models

[top] Model #146: Flying Jeep

NACA and later NASA had an interest in personally-controlled vehicles. For an interesting outside article on flying jeeps and other flying platforms, see Vectorsite.net.

[top] Model #148

[top] Model #149

[top] Model #153

[top] Model #154

[top] Model #1665

[top] Modified 119 Model

[top] Modified 119 Model and 108F Model

[top] Model #321

[top] Model #364

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